A model where a driver is assumed to disengage attention, etc but then be expected to rengage in a fraction of a second to respond to an anomalous event is fundamentally at its core flawed I think. It's like asking a human to drive and not drive at the same time. Most driving laws assume a driver should be alert and at the wheel; this is what...? Assuming you're not alert and at the wheel?
As you're pointing out, this leads to a convenient out legally for the manufacturer, who can just say "you weren't using it correctly."
I fail to see the point of autopilot at all if you're supposed to be able to correct it at any instant in real-world driving conditions.